Question

A rail gun accelerates a projectile from rest by using the magnetic force on a current-carrying wire. The wire has radius r = 5.23·10-4 m and is made of copper having a density of ? = 8960 kg/m3. The gun consists of rails of length L = 1.50 m in a constant magnetic field of magnitude B = 2.15 T, oriented perpendicular to the plane defined by the rails. The wire forms an electrical connection across the rails at one end of the rails. When triggered, a current of 1.01·104 A flows through the wire, which accelerates the wire along the rails. Calculate the final speed of the wire as it leaves the rails. (Neglect friction.)